Flap mechanism



m 1 n NW 4 e n 1 w wmfi m 6 .M 2 a M d M S M A a H Y B 1952 R. F.DONOVAN FLAP MECHANISM Filed Dec. 51, 1948 R. F. DONOVAN FLAP MECHANISMOct. 21, 1952 4 Sheets-Sheet 5 Filed Dec. 51, 1948 INVENTOR.

Raymond 1 pa/uwan ATTOHIYK? R. F. DONOVAN FLAP MECHANISM Oct. 21, 1952 4Sheets-Sheet 4 Filed Dec. 51, 1948 INVENTOR.

BY Raymond Donovan Patented Oct. 21, 19 52 UNITED STATEApplicationDecember 31, 1948, SerialNo.'68,633 y Y ZCIaims. (01124543)Thisinvention relates to movable aircraft surfaces and particularly toimprovements in auxiliary airfoils or flaps. I I l In present day highperformance aircraft, it is vital that all movable surfaces'and theiroperating mechanisms be absolutely dependable, simple in constructionand operation, and compact and clean in design. In addition to the-aboverequire ments, new aerodynamic loading problems must be considered inthat the flaps must greatly rel duce air speeds for safer landings andmust provide considerably more lift to insure adequate lift for take-01fand cruise conditions. With the modern design of high speed airfoils andtheir greatly increased areodynamic loading, movable airfoilssuch asflaps must be structurally ade-r quate.

"Therefore, it is an object of this invention to provide an auxiliaryairfoil or flap in conjunction with a main aircraft lifting surface forefliciently varying the area, chord and camber' of the main liftingsurface; I l I Another object of this invention is to provide animproved aircraft flap mechanism which in- Y sures positive control'ofthe flap for intermediate positions in its operative range. a i

to provide an extensible flap which can withstand extremely Anotherobject of this invention is high aerodynamic loads in its cruise orpartially extended and deflected positionas a result of having the flaprigidly supported at itstrailing edge by the main wing. l

Another object of this invention is to provide actuating and controllingmechanism's which are completely housed within the main wingso thatprotrusions from the main wing areleliminated;

These'and other objects will become apparent from'the following-detaileddescription of the ac'-- companying drawings wherein one embodiment ofthe invention is illustrated. V ,In these drawings: I l v Fig.1 is apartialplanviewlof an airplane and 7 main wing including (the flaps ofthis invention;

the flap and accomin the fully S OFFICE aclin'zif i g M FLAP EoHsNIsM- yfl F- Donovan, Dalla srTexi, assignor to H y United AircraftCorporation, East. Hartford, Court, a corporation of De laware M Fig. 8is a perspective view showingthe cable actuating system for the flapextending; mechanism. i I

In Fig. 1 the airplane fuselage Tcarriesa main wing 8 which includes apair of flaps l0 disposed on each side of; the fuselage? n m As shownmost clearly in Fig. 12,-; each flap 'll); islocated between and carriedby a;pair of truck assemblies 12 "and-I4 each of which-has agpair of"front rollers l6panda painyofrear rollers 13;

a which slidably engage 111113,]; wingtracks 20 (Figs 4); only one'ofthe tracks being shown inFigs. 4-7- for convenience of illustration.Thetrack-zmis located between wing-ribs 2,2 and (shown in phantom inFig. 2)? and as seen' more clearly-in; Fig: 6; the trackiulhas a slightjoggle 26 atiits. forward. end but otherwise it is-.essentiall astraight track housed within the wing proper; and slopes downwardlytoward the rear. n

ThetruckM has fore and aft connections :the aft end being securedadjacent the leading edge of: the. flap l 0 at the point 28. Two pairsofupstand ing ears 30'and32 are integrally. formed onthe forward end ofthe truck Manda cable carried cross pin34 is securedthereto to-provideana'ctu-; ating connection for theytruckn Themain' body portion of truckl4 has thereinaniinternal track 36 in whicha carriage 38 is adapted'GOYmOVB in'a limitedfore and aft direction.y The carriage 38 a hastwofurcations 40 and andia connecting bolt therein for supporting one endof a springstrut 146 and a radius'rod "48; "I'he other end of the springstrut 46 is attached .to a depending? flange 49'on the aftiendofthetruck l4 while the other end of radius 'rod 48 is pivotally connected tothe lower surface of the flap at a point' aft of thelattersmid-chordlocation. 1 l

- As :can be'seen most clearly in Fig. 2, the flap H1 has a stud 52located near its"trailing edge" for-cooperation with a channel 54 inthemainwing. The stud serves as an aft support forithe' flap for itscruiseposition of extension since: underthese conditions-the aircraftwillbei'flying at relatively high "speeds and high aerodynamic:

loads will be imposed thereon. In this manner: relativelythinairfoilsqcan' be made structurally,

adequate for high speeds.

Fig, 8 illustrates the cable and actuating tem of: this invention. Inthis view actuatingstruts 56. and 58are1ocated ina spanwise posi-v tionnear'the trailing edge of' the mainwing just forward of their respectivemovable flaps'llla The extension or compression of struts 5,6,and 58imparts movement to the flapsl Only the; movements of thecright-handstrutuvill be de-lz tached thereto which rides over pulleys 80, 82',

84 and 86 and is connected to the lowermost A cable 88 runs from thecenter connection of outboard yoke Glover connection of yoke 62.

pulleys 90, 92, 94, 96, 98, I08 and I06 to the center connection of theinboard yoke [83. inthe left-hand wing. Cable I04 makes a similarconnection from the yoke I85 in the left wing to" the right wing therebyinterconnecting the right and left flap actuating systems. Thisinterconnection insures simultaneous operation of both flaps in theevent of failure of either strut 56erstrut 58. s I

Cables 66 and 18 each carry the dogs 106A and H18, respectively, whichin turn support a cross pin connection 34 as seen most clearly in Fig.3.

Thus it can be seen that when rod 60 of strut- 58 moves to the right theyokes 62 and 64 are pulled to the right, thereby moving dogs I06 and I88simultaneously in a forward direction, thereby applying uniform motionto the wing trucks [4 and causing movement of flap It).

It is, of course, desirable and necessary to move the rightflap and theleft flap simultaneously. Accordingly; the crossed cables 88 and I04synchronize the flap movements and, in the event of failure of eitheractuating strut, the

remaining operative strut can operate both flaps.

The flaps normally have four basic positions as shown on Figs. 4, 5, 6"and '7'. Fig. 4' shows the flap in its completely retracted or full upposition. In this position of the flap it is apparent that theupstanding ears 32' of the dog I08 are the extreme forward positionand-the truck i4 is in a fully forward position in wing track 28, whilecarriage 38 isi'in the aft position in truck track 36; the. carriage 38'being biased in this position by spring'strut 46. At' the same time thestud 52 is engaged with the. forward end of channel 54.v This deflectedposition of flap l0 provides a rigidlycarried airfoil and highspeedaerodynamic forces are satisfactorily counteracted since the flap isfirmly supported at its forward and aft ends by wing carried structure.

Fig. indicates the position of the flap. and mechanism in the 4deflected or cruising position. This small deflection is accomplished asthe front pair of rollers l6 move into the lower; portion of joggle 26,thereby causing nap in to rotate slightly about point 28 of truck l4and. point 58.. Stud 52 on flap. [0 moves to the end of channel 54 butis. still maintained in slot 54 to give additional support to. the flapwhen the airplane is cruising at moderately high speeds. Channel 54 andtrack 14 are parallel; accordingly, the outward downward extension ofthe flap is due to the slope of the track l4 and slot 54 in relation tothe wing. However, beyond this cruise position the flap is extendedsubstantially in linear relation to. the wing until the full extensionposition is approached at which time the flap is pivoted downwardly in amanner to be described hereinafter. However, the carriage 38 up to thepoint of downward pivotation of the flap is held in the aft end of thetruck track 36, being maintained in that position by the pre-loadedspring strut 46.

When the flap is moved from the up position to the cruising position,the trucks in the inboard and outboard wing rib tracks move aftapproximately; 3.6 inches. The curved portion or joggleof the wing ribtracks 26 causes the .forward end of the truck to move downward and theaft end of the truck to move upward, thus causing the forward portion ofthe flap to move upward and rotate the aft portion of the flap downward4 degrees such that the upper surface of the flap remains in contactwith the wing upper trailing edge. It is obvious, then, that the uppercambered surface will remain in juxtaposition with the upper wingsurface trailing edge so that no gap will exist between the wing andflap during the relatively high speed cruise condition. The 'flap stud52. remains within its channel 54 for the cruising position in order toprovide a large torsional support arm for the flap for the relativelyhigh speed (approx; 350 M; P. IL). This special cruising position isprovided to keep the airfoil within the low drag regime. when carryingadditional weight such as auxiliary fuel tanks or bombs.

In Fig. 6, a profile view is shown of the flap in a partially deflected-(approx. 27 or takeoff position wherein the flap has reached itsmaximum aft travel and begins to be deflected downwardly. Althoughit-has been determinedthat. this amount of. flap deflection provides anadequate lift increase for take-oif for certain tion to the truck l4 andcausing the flap It) to rotate about the relatively fixed pivot point58. The relative movement between the truck l4 and the carriage 38, itis apparent, must be made against the bias of spring strut 46 which atthis time is being compressed.

As seen. in Fig. 7 the flap I0 is in its fully (50) deflected position.In this position truck I4 has been moved to its full aft position, andinasmuch as the aft movement of carriage 38 has been stopped by theabutments 39, carriage 38 is forced to the forward end of truck track36, thereby causing flap [0 to rotate downwardly to its fully deflectedposition. It should be noted tain amount of pivotal freedom is ailordedto the radius rod 48 about the bolt 44 to prevent an overstress of theflap mechanism which would result from the sloping aft movement of truck14.

When the flap is moved from the cruising position to the take-offposition, the trucks on the inboard and outboard Wing rib tracks moveaft approximately 90% of their full travel. When the trucks have movedback of their full travel, the carriage comes up against a stoplock 39at 'both' the inboard and outboard tracks. The carriage then stops, andthe truck'moves past the carriage while the radius rod rotates somewhataround the bolt 44 due to rotational motion of the flap. During themotion from cruising position to take-off position, the spring strut,because of its preloading, keeps the carriage in a fixed positionagainst its stop relative to the truck; also, air loads acting upon theflap cause it to tend to trail" thereby loading the carriage against itsstop in the truck.

When the iiap is moved from the take-oil position to the landingposition, the carriage remains against the stop 39, and the trucks inthe inboard and outboard wing rib tracks move aft relative to thecarriage. The aft movement of the truck causes the flap to rotate sincethe end of the radius rod is restrained from translational movement.

The spring strut between the carriage and the truck has sufficientpreloading to overcome the hinge moment tending to deflect the flap dueto the dead weight of the flap such that when the flaps are checked foroperation on the ground,

without air loads acting thereon, the flap Will always be in adeterminate position.

As a result of this invention it is apparent that an improved flapmechanism has been provided whereby the flap can be partially extendedin a relatively horizontal plane for intermediate flight conditionswhile the flap can be downwardly deflected toward the end of its aftmovement to provide adequate drag in landing.

Further as a result of this invention an improved fiap mechanism hasbeen provided which permits a partial flap extension for high speedcruise conditions while adequately supporting the flap so that the highair loads accompanying such flight conditions can be withstood. Alsoduring such high speed cruising the upper cambered surface of the flapis maintained in close contact with the upper wing surface therebyproviding a continuous streamlined surface having higher liftingqualities without a large increase in drag.

Although only one embodiment of this invention has been illustrated anddescribed herein, it is apparent that various modifications and changescan be made in the arrangement of the parts without departing from thescope of this novel concept.

What it is desired by Letters Patent is:

1. In an aircraft, a main wing, an extensible flap, means for mountingsaid flap on said wing, mechanism in said wing for extending said flapsubstantially horizontally in relation to said wing, said mechanismcomprising a track carried in a fore and aft position in said wing, atruck having fore and aft rollers engaging said track and having apivotal connection to the forward end of said flap and having a fore andaft slot, and a carriage slidable within said slot and including a rigidextension member connected to said flap at a point remote from saidpivotal connection, biasing means comprising a spring loaded strut oneend of which is connected to said truck and the other end connected tosaid carriage for ing its initial movement while said stud is engaged insaid channel including a J'oggle in the forward portion of said trackwhereby said extension member and said pivotal connection are displacedwhen said forward roller moves into said joggle, and means forincreasing the defiection of said flap relative to said wing when saidstud moves out of the open end of said channel including a stop on saidwing engageable by said carriage for overcoming said biasing means.

2. In an aircraft having a mainwing, a pair of extensible flaps disposedon either side of the longitudinal centerline of said main wing beneaththe trailing edge thereof, means for mounting said flaps on said wing,mechanism in said wing for extending each of said flaps substantial- 1yhorizontally in relation to said wing, said mechanism comprising a trackcarried infa fore and aft position in said wing, a truck having fore andaft rollers engaging said track and having a pivotal connection to theforward end of said flap and having a fore and aft slot, and a carriageslidable within said slot and including a rigid extension memberconnected to said flap at a point remote from said pivotal connection,biasing means comprising a spring loaded strut one end of which isconnected to said truck and the other end connected to said carriage fornormally maintaining said carriage in the aft portion of said slot,means for guiding said flap during its initial aft movement including achannel in said wing open at its aft end and a stud on said napcooperating with said channel, means for imparting a slight deflectionto said flap during its initial movement while said stud is engaged insaid channel including a joggle in the forward portion of said trackwhereby said extension member and said pivotal connection are displacedwhen said forward roller moves into said joggle, means for increasingthe deflection of said flap relative to said wing when said stud movesout of the open end of said channel including a stop on said wingengageable by said carriage for overcoming said biasing means, actuatingmeans operatively connected to each of said flaps, and means forinterconnecting said actuating means to move both flaps by either ofsaid actuating means.

RAYMOND F. DONOVAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,137,879 Ksoll Nov. 22, 19382,207,453 Blume July 9, 1940 2,222,435 Ksoll Nov. 19, 1940 2,235,146Fowler March 18, 1941 2,352,062 Zap June 20, 1944 2,376,636 Thompson May22, 1945 2,379,274 Boyd June 26, 1945 2,423,984 Knoll July 15, 19472,426,785 Naumann Sept. 2, 1947 FOREIGN PATENTS Number Country Date417,898 Great Britain Oct. 15, 1934 454,556 Great Britain Sept. 28, 1936

